1. Field of the Invention
The present invention relates to radio frequency circuits; more specifically, probes for testing radio frequency circuits.
2. Description of the Related Art
In the past, radio frequency circuits were tested usually using radio frequency (RF) couplers. Radio frequency couplers were built into the circuit to provide test points to monitor the radio frequency signal in the circuit under test. This technique had the disadvantage of using precious circuit card real estate as well as adding the expense of RF couplers.
Another technique for testing RF circuits involved using RF test probes with a bayonet type tip. One of the bayonet tips was used as a ground and the second bayonet tip was used to contact a radio frequency conductor such as a microstrip in the circuit under test. The bayonet tips often provided poor contact with either the microstrip or ground. Additionally, the bayonet probe affected the circuit under test and thereby distorted the RF signal to be measured.
The present invention provides an inexpensive RF test probe that provides a consistent measurement of an RF signal while having minimal effect on the circuit under test. In one embodiment of the present invention, an RF test probe comprises a return conductor and a probing conductor. The probing conductor is positioned within an insulator, and a termination such as a 50 ohm resistor is electrically positioned between the ground conductor and probing conductor. The probe is used by placing a portion of the insulating material that surrounds the probe conductor in contact with a circuit such as an RF microstrip carrying an RF signal to be monitored.